The present invention relates to a resin pipe joint in which a flare portion of a pipe and a joint body are sealed. The present invention relates to a resin pipe joint applied to feeding, for example, ultra pure water, a high purity medical liquid or the like used for peripheral equipment in the production of semiconductor, and to piping in chemical industry.
As an example of a conventional resin pipe joint, FIG. 3 shows a cross-sectional view of a pipe joint made of fluororesin proposed in JP4 (1992)-132290U. In the resin pipe joint shown in FIG. 3, an inner ring 2 is pushed in the inside of the end portion of a tube 1. The inner side of a joint body 3 is fitted to the outer side of the end portion of the tube 1 and the end portion of the inner ring 2. A cap nut 4 is threadedly fitted to the joint body 3, thereby forming a first sealing portion 5 in which the inner ring 2 is pressed into contact with the joint body 3 and a second sealing portion 6 in which the inner ring 2 and the outer side of the end portion of the tube 1 are pressed into contact with a receiving port of the joint body 3.
Moreover, as another example of a conventional resin pipe, FIG. 4 shows a cross-sectional view of a pipe joint made of fluororesin proposed in JP7 (1995)-103949B. In the resin pipe joint shown in FIG. 4, a joint body 8 is fitted to an expanded-diameter portion 7a that was previously provided on the end portion of a tube 7.
The cap nut 9 is threadedly fitted to the joint body 8 by way of a female screw 9a formed on the cap nut 9 and a male screw formed on the joint body 8. The threaded fitting between the joint body 8 and the cap nut 9 causes the tube 7 to be pressed into contact with the inclined portion 8b of the joint body 8, thereby forming a sealing portion.
Furthermore, a concave portion 7b is provided on an inner surface of the tube 7 in the circumferential direction and a convex portion 8a is provided on an outer surface of the joint body 8a in the circumferential direction. The concave portion 7b is fitted to the convex portion 8a, and thereby the tube 7 is latched by the joint body 8, and the drop-off of the tube 7 from the joint body 8 is prevented.
However, the above-mentioned resin pipe joint has the following problems. Namely, in the resin pipe joint proposed in JP4 (1992)-132290U, the contact pressure generated when the cap nut 4 is threadedly fitted to the joint body 3 is spread over a side area including the first sealing portion 5, the second sealing portion 6 and an edge portion 4a of the cap nut 4.
Therefore, on the second sealing portion in which the receiving port of the joint portion 3 is in contact with the inner ring 2 in a large area, a sufficient contact-pressure may not be applied to the tube 1. In particular, in the case where a high temperature medical liquid is allowed to be circulating, the wall thickness of the tube 1 is reduced, for example, in the edge portion 4a of the cap nut 4, clearance occurs between the cap nut 4 and the inner ring 2. Consequently, the contact-pressure of the tube 1 further is lowered, which may cause the tube to drop off the joint body.
Furthermore, in the resin pipe joint proposed in JP7 (1995)-103949B, when the cap nut 9 is threadedly fitted to the joint body 8, since there is no guide structure for guiding the cap nut 9 straight with respect to the joint body 8, the cap nut 9 is rocked from side to side. Therefore, the cap nut 9 may threadedly be fitted to the joint body 8 with fitting between the female screw 9a formed on the cap nut 9 and the male screw 8c formed on the joint body 8 being insufficient. In the very worst case, the cap nut 9 is forced to be fitted threadedly to the joint body 8 with a thread being damaged, which may lead to leakage of the medical liquid during circulation.
The various embodiments of the present invention provide a resin pipe joint capable of securing a high sealing property, threadedly fitting a cap nut smoothly, and preventing the drop-off of the pipe and leakage of liquid.
In some embodiments, the resin pipe joint of the present invention includes a pipe and a joint body, the pipe being fixed in the joint body in a state in which the pipe being inserted into a through hole of the joint body, wherein a tapered flare portion is formed on the end portion of the pipe; the through hole of the joint body has an expanded-diameter portion and a reduced-diameter portion whose diameter is smaller than the diameter of the expanded-diameter portion; an inclined portion, which can be brought into contact with the flare portion of the pipe, is formed on a portion having a level difference between the expanded-diameter portion and the reduced-diameter portion; the pipe is inserted to the expanded-diameter portion so that the flare portion is brought into contact with the inclined portion; an annular member is inserted and attached to the inner peripheral surface of the expanded-diameter portion, and the through-hole of the annular member passes through the pipe; a screw portion of a pipe clamping member, which the screw portion is formed on the inner peripheral surface, is threadedly fitted to the screw portion formed on the outer peripheral portion of the joint body, whereby the pipe clamping member presses the annular member, a tapered chamfered portion formed on the end portion of the through hole of the annular member is pressed into contact with the flare portion of the pipe, the flare portion of the pipe is pressed into contact with the inclined portion of the joint body, an extending portion being integrated into the annular member is formed on the opposite side to the chamfered portion of the annular member, the extending portion guides the pipe clamping member while passing through an opening portion of the pipe clamping member when the pipe clamping member is threadedly fitted to the joint body, and and the end face of the extending portion and the end face of the pipe clamping member at the side of the extending portion are substantially in the same plane.
According to the such a resin pipe joint, clamping force by the pipe clamping member and the joint body can be concentrated on the flare portion of the pipe. Therefore, a high sealing property between the pipe and the joint body and to enhance the prevention of the drop-off of the pipe from the joint body can be obtained. Furthermore, when the pipe clamping member is clamped, it is possible to suppress a side-to-side rocking motion of the pipe clamping member, to carry out the threadedly fitting of the cap nut to the joint body smoothly, and to prevent a thread from being damaged due to the threadedly fitting.
Furthermore, when the pipe clamping member is threadedly fitted to the joint body, it is possible to utilize the location relationship in which the end face of the extending portion and the end face of the pipe clamping member of the side of the extending portion are in substantially the same plane as a guide for clamping the pipe clamping member. As a result, the clamping can be carried out efficiently.
In some aspects, the flange portion is formed on the end portion of the flare portion of the pipe. With such a resin pipe joint, it is possible to enhance the prevention of the drop-off of the pipe from the joint body.
In some aspects, the extending portion has an annular shape and has an outer diameter being smaller than the outer diameter of the annular member. According to such a resin pipe joint, it is possible to form an extending portion with a simple structure.
In some aspects, the pipe is made of resin and the flare portion is formed by thermally melting the end portion of the pipe. According to the above-mentioned resin pipe joint, as compared with the case where the flare portion is formed simply by thermal deformation or is formed by the deformation by force, the change in the size of the flare portion of the pipe that is a pressure-contact portion is reduced, and a sufficient strength for preventing the drop-off of the pipe from the joint body can be secured.